GLYPHOSATE OR SETHOXYDIM FOR QUACKGRASS (ELYTRIGIA-REPENS) CONTROL IN2 TILLAGE REGIMES

Field experiments were conducted at Lacombe and Ellerslie, Alberta, Ca nada, to study the interaction of tillage with glyphosate and sethoxyd im on quackgrass shoot and rhizome biomass, rhizome bud viability, and crop yield. Glyphosate was most effective in the conventional tillage regime, whereas sethoxydim was effective only in conventional tillage . Tillage reduced viable rhizome buds more than shoot or rhizome bioma ss. The large tillage effect on quackgrass control with either herbici de would likely be diminished in zero tillage systems that employ pres eeding burn-off or preharvest application of glyphosate. Under zero an d conventional tillage, glyphosate at 220 g ha(-1) often was as effect ive as glyphosate at 880 g ha(-1). A split application of glyphosate a t 220 g ha(-1) in the fall and spring was as effective as a single 880 g ha(-1) treatment in conventional tillage, and sometimes more effect ive than 880 g ha(-1) in zero tillage. Glyphosate followed by sethoxyd im was usually no better than glyphosate alone. Short-term split appli cations of sethoxydim offered no consistent advantage over single appl ications.